AmAJP°rii! i87h9arm  }       Abietene,  a  New  Hydrocarbon.  179 
1  stood  a  small  quantity  of  the  abietene  in  contact  with  217th  of  its 
bulk  of  strong  sulphuric  acid,  and  after  24  hours,  pouring  it  off  from 
the  dark  brown  resinous  sediment  which  had  formed,  distilled  the  oil. 
It  boiled  as  before  at  '1010.  It  was  again  placed  in  contact  with  sul- 
phuric acid,  when  a  slight  shade  of  brown  only  appeared  to  settle  out, 
and  then  re-distilled.  It  came  over  at  1010.  The  quantities  thus 
■obtained,  both  of  the  oil  distilling  at  1010  and  of  the  brown  resinous 
substance,  were  too  small  to  examine  in  detail.  It  seems  probable, 
however,  that  they  would  be  found  to  correspond  to  the  terebene  and 
colophene  obtained  from  ordinary  oil  of  turpentine. 
Jetton  of  Nitrosyl  Chloride  (NOC1). — This  reageant  has  only  recently 
been  applied  to  the  study  of  organic  compounds.  Tilden,  who  has 
given  most  study  to  the  subject  (u  Berichte  der  Chem.  Ges.,"  vii,  pp. 
597,  1025,  ana<  x?  P*  9°8),  finds  that  the  compounds  produced  by  its 
action  upon  the  different  terpenes  are  especially  characteristic  and 
stable  compounds.  Indeed,  they  seem  to  be  so  distinctive  that  Tilden, 
as  quoted  by  Attfield  ("Attfield's  Chem.,',  8th  edition,  p.  461),  classi- 
fies the  terpenes  in  part  on  the  basis  of  the  nitroso-compounds 
obtained  from  them.  I  therefore  tried  the  action  of  nitrosyl-chloride, 
prepared  by  the  action  of  common  salt,  upon  nitrosyl -sulphate  (lead- 
chamber  crystals),  upon  abietene.  The  oil  was  cooled  by  a  freezing 
mixture,  and  the  gas  allowed  to  bubble  through  it  for  several  hours. 
A  small  amount  of  a  flocculent  precipitate  formed,  from  which  the  oil 
was  decanted,  and  the  precipitate  was  then  washed  with  alcohol  and 
cheated  with  alcoholic  solution  of  caustic  soda,  in  order  to  convert  the 
nitrosyl-chloride  compound  of  the  terpene,  which  is  unstable,  into  the 
more  stable  nitroso-terpene.  A  white  substance  was  thus  obtained, 
which  should  have  been  the  sought-for  nitroso-compound.  It  was  on 
examination,  however,  found  to  be  largely  chloride  of  sodium,  which 
formed  on  the  treatment  with  alcoholic  soda  solution,  and  which  was, 
of  course,  insoluble.  How  much  of  the  desired  nitroso-compound 
was  present  in  it  could  not  be  readily  ascertained  with  the  small 
amount  in  hand.  So  the  question  of  the  nitroso-compounds  I  will 
have  to  leave  unsettled  until  larger  amounts  of  the  abietene  can  be 
examined. 
Tilden's  classification  of  the  terpenes  (all  essential  oils  of  the  com- 
position C10H16  or  isomeric  with  them)  is  the  following  : 
"A  turpentine  group  of  true  terpenes  (C10H16)  whose  members  boil 
